In a saucepan, mix milk with water, add butter and salt. Bring everything to a boil.
Reduce the fire to a slow one. Stir the milk with a wooden spatula so that the liquid rotates in a circle, then pour in the flour and mix quickly. Stir until the dough thickens and begins to lag behind the walls of the pan; this will take about a minute. Transfer the finished dough into a bowl and let stand for 10 minutes.
Add one egg to the dough after each well mixed.
Lubricate the baking tray with vegetable oil and squeeze out the dough using a pastry syringe or simply lay out with a spoon.
Bake for 20 minutes at 190 degrees, turn off the oven and let the cakes stand in the heat for another 10 minutes.
For the filling, beat with a mixer soft butter with condensed milk.
Use a pastry syringe to fill the cakes with cream.
Pour the finished cakes with melted chocolate, let it harden a little and you can serve.